The invention relates to a toner for developing a static latent image to be used as a copy machine and a printer, and an image forming apparatus.
An impurity, particularly a low molecular weight ingredient having a smell, contained in a toner for developing a static latent image usually used in electrophotography tends to cause an undesirable condition such as giving off an unpleasant odor when the container of the toner is opened at the time of the use of the toner.
A heat-fixing method is usually applied for fixing a toner image onto a copy paper sheet. A heat-roller fixing method is widely used as the heat-fixing. Such the method is extremely suitable for fixing since the heat efficiency for fusing the toner image to adhere it onto the image receiving element is very high and the image can be rapidly fixed.
In some cases, however, an unpleasant odor is given to the operator since the toner image is heated so as to release a very small quantity ingredient contained in the toner. Recently, the chance of to use the copy machine or the printer near a person such as in an office is considerably increased. The chance of the domestic use of such the apparatus is also increased. Consequently, the case is increased in which the odor given off from the toner gives unpleasant feeling to the using person using it. The social concern with the smell is recently raised and the bad odor tends to be extremely evaded even though the fragrant is liked.
One cause of the bad odor given off from the electrophotographic apparatus is generation of ozone by corona discharge. However, the odor of ozone is dramatically reduced by technological innovation such as the development of a contact charging method using a roller charging or a brush charging or of a corona charging device in which the ozone generation is considerably inhibited. Consequently, the case of the unpleasant feeling caused by the toner odor is relatively increased.
In a case, a filter for absorbing the odor is attached with the apparatus. However, such the means accompanies a disadvantage in the production cost and a trouble as to the maintenance of the deodorizing function such as periodical exchange of the filter.
A method by means of reducing the impurity in the binder resin has been known as the means for decreasing the odor caused by the toner. For example, Japanese Patent Publication Open to Public Inspection, hereinafter referred to as JP. O.P.I, Nos. 64-70765, 64-88556 and 8-328311 each proposes decreasing the odor by reducing the monomer remained in the binder resin. JP O.P.I. Nos. 7-104515 and 7-104514 each describes that the reducing of the evaporative ingredient is insufficient to inhibit the toner odor and a technology to remove the odor of the raw material since the evaporative matter formed by decomposition of an chemically instable substance contained in a very small amount in the raw material of the binder resin.
JP O.P.I. No. 8-171234 describes that the causing substance of the odor is an oxidation product of benzaldehyde contained in the toner, and discloses the trial for reducing content of benzaldehyde. Moreover, JP O.P.I. No. 9-230628 describes a contrivance for reducing the odor without bad influence on the fixing ability of the toner by reducing the using amount of alkyl mercaptane until the minimum amount necessary for making the basic property of the toner.
JP O.P.I. No. 3-105350 describes an attempt to add an alkyl betaine compound to the toner as a substance capable of reacting with or absorbing the odor substance. Furthermore, JP O.P.I. No. 2-240663 describes a deodorizing method by which the toner is contacted with a deodorant for 5 hours or more in the processes of crashing and classifying of the toner. However, a long producing time is required and the odor given off after the production cannot be reduced by this method.
The countermeasures by the foregoing methods accompany with difficulty since the amount of the odor substance capable of being perceived by man is very small.
It is important, however, to consider the problem of the odor from the viewpoint of that it is difficult to judge the odor is perceived by man as a good smell (fragrant) or a bad odor and a non-smell condition is pleasant or not for man since the perception of man is delicate.
From such the viewpoint, it is necessary to known a technology for precisely evaluating and designing the quality of the odor caused by the extremely small amount of the contained substance according to a objective norm, and to know that what smell given off in what degree is perceived by man as pleasant smell according to the evaluation and the design.
The object of the invention is to precisely evaluate and design the smell given off from the image forming apparatus such as the copy machine or the printer, which are become to be frequently used near man, and to make the smell to a pleasant smell for man. The evaluation and the design of the toner is previously carried out from the viewpoint of that the pleasant smell is given off in the image forming process since the major cause of the smell given off from the image forming apparatus is the toner for developing the static latent image.
A method is found by the inventors, by which a slight and delicate smell can be objectively evaluated and the standard of the pleasant smell can be defined according to the results of the evaluation. Thus the invention can be attained.
The object of the invention can be achieved by applying any one of the following constituents.
1. A toner for developing a static latent image, wherein a smell of the toner has a cos xcex8 of from 0.990 to 0.998 as to the smell of styrene and a cos xcex8 of from 0.986 to 0.994 as to the smell of n-butyl acrylate in the smell space formed by styrene and n-butyl acrylate.
2. A toner for developing a static latent image, wherein a smell of the toner has a cos xcex8 of from 0.990 to 0.998 as to the smell of styrene and a cos xcex8 of from 0.991 to 0.999 as to the smell of mercaptocarboxylic acid ester in the smell space formed by styrene and mercaptocarboxylic acid ester.
3. An image forming apparatus fixing a toner image onto a recording material by heating, wherein the image forming apparatus emits a fragrant smell having a cos xcex8 of from 0.990 to 0.998 as to the smell of styrene and a cos xcex8 of from 0.986 to 0.994 as to the smell of n-butyl acrylate in the smell space formed by styrene and n-butyl acrylate.
4. An image forming apparatus fixing a toner image on to a recording material by heating, wherein the image forming apparatus emits a fragrant smell having a cos xcex8 of from 0.990 to 0.998 as to the smell of styrene and a cos xcex8 of from 0.991 to 0.999 as to the smell of mercaptocarboxylic acid ester in the smell space formed by styrene and mercaptocarboxylic acid ester.
The angle between the vector of the smell causing substance and that of a sample is determined and the cosine of the angle cos xcex8 is calculated. It can be considered that the smell of the sample is nearer the smell of the smell causing substance when the angle of the vector is smaller or the value of the cos xcex8 is larger.
For example, when the vectors of Toner A and Toner B and the reference substance are as shown in FIG. 1, cos xcex8 B is larger than cos xcex8 A in this case. Consequently, it can be concluded that the smell of Toner B is nearer the smell of the reference substance than the smell of Toner A.
In the invention, styrene, a mercatocarboxylic acid ester and n-butyl acrylate are used as the reference substance. As the mercaptocarboxylic acid ester, n-octyl-3-mercaptopropionic acid ester is used.
It has been found by the inventors that a smell different in some degree from, not the same as, the smells of these reference substances is a pleasant smell source so that the working efficiency can be raised. Furthermore, it has been unexpectedly found that the working efficiency is also lowered when the smell is largely different from that of the reference substance. It is considered that the working efficiency is lowered by a sense of incompatibility caused by the smell different from that usually perceived from the copy machine of the printer customarily used even though the reason of such the effect is not cleared yet. It is supposed that the working efficiency of man can be raised by giving the slightly different smell without feeling of the smell difference. Consequently, it is concluded that it is important to control the smell of the toner so that the gradient of the vector as to the reference substance cos xcex8 is within the specified range. Thus the object of the invention is attained.
The working efficiency of man is lowered when the smell is without the range.
The cos xcex8 as to the reference samples in the smell space represents the cos xcex8 measured by the following method.
As the sample for measuring, 0.1 g of a toner is put into a sample bag made of poly(ethylene terephthalate) having a volume of 2 liter.
The sample bag is filled by nitrogen and the bag including the toner is heated for 30 seconds by a hot plate heated at 160xc2x0 C.
Preparation of Reference Sample
Reference sample of styrene smell: In a 2 liter sample bag, 0.2 ml of saturated styrene gas is put and diluted by nitrogen gas.
The saturated gas is gas taken near the liquid surface in the bottle by a micro syringe. The bottle is stored at an ordinary temperature under a closed condition.
Reference sample of n-butyl acrylate smell: In a 2 liter sample bag, 0.2 ml of saturated n-butyl acrylate gas is put and diluted by nitrogen gas.
Reference sample of mercaptocarboxylic acid ester smell: n-octyl-3-mercaptopropionic acid ester is used as the reference substance. In a 2 liter sample bag, 0.5 ml of saturated n-octyl-3-mercaptopropionic acid ester gas is put and diluted by nitrogen gas. Then the bag is stood for 1 hour.
Measuring Condition
Measuring Apparatus: Fragrance and Flavor Analyzer FF-1
Manufactured by Shimazu Seisakusyo Co., Ltd.
Temperature of sensor chamber: 60xc2x0 C.
Current amount of sampling: 165 ml/min.
Preliminary sampling period: 10 sec.
Sampling period: 45 sec.
Temperature of collecting tube: 40xc2x0 C.
Dry Purge
Temperature: 40xc2x0 C.
Current amount: 500 ml/min.
Period: 45 sec.
Desorption
Temperature of collecting tube: 220xc2x0 C.
Current amount: 20 ml/sec
Period: 90 sec.
Measuring times for one sample: 5